This invention relates generally to underground storage reservoirs in combination with above-ground shelters for accessing such reservoirs, and more particularly relates to an integrated underground fluid storage reservoir and above-ground canopy support system.
Various types of materials are stored beneath the surface of the ground for access through above-ground dispensing and/or distribution facilities. One class of such materials includes fluids such as fuels for automotive and heating uses. Typically, these storage installations include a fluid reservoir that is buried beneath ground level within an excavated pit. A backfill material is typically used to surround the storage tank to achieve a buried condition for the reservoir. Pea gravel is a standard backfill material in the industry because of its ability to quickly achieve a substantially settled condition. Sand has also been used as a backfill material.
In the case of underground storage reservoirs at automobile service stations, one or more reservoirs containing automobile fuel are typically located upon the service station premises at a location some distance away from the pumps used for dispensing the fuel to automobiles. In such an arrangement, the underground storage tanks can be filled, such as by tanker trucks, without impeding the ability of the service station to continue operating. This is because the tanker trucks can access ports or manholes for filling the underground storage tanks in the remote area of the service premises away from the dispensing units.
However, locating underground storage tanks for fluids such as automobile and heating fuels at a distance away from the dispensing location requires a significant amount of underground piping for connecting the dispensing units to the underground storage tanks. These pipes sometimes require maintenance and/or service operations. Therefore, these pipes must be accessible to service and maintenance personnel at times. A typical automobile service station, however, includes one or more sections of concrete driveway covering a substantial portion of the service station premises, in order to provide customers with sufficient maneuvering access to the typical several dispensing units. This substantial concrete driveway also provides sufficient access to the underground storage reservoir filling ports by tanker trucks. This type of arrangement, however, makes accessing the underground piping network connecting the storage tanks with the dispensing pumps expensive, difficult and time consuming.
Automobile service stations are often designed to include multiple dispensing units, commonly referred to as “pumps,” “multiple pump dispensers” or “MPDs”, from which multiple customers can access the underground storage reservoir or reservoirs at the same time. These dispensing units are often located at multiple service islands located upon the service station premises. Since automobile fuel is commonly sold in multiple grades, the different fuel grades can be stored within a single partitioned reservoir or within multiple reservoirs. Extensive underground piping is therefore typically required in order to distribute different grades of fuel to the different dispensing units located at the various service islands.
In addition, the increasingly popular recovery of fuel vapors from automobile fuel tanks upon filling involves the transport of these vapors to the underground storage reservoir (Phase II recovery). These vapors are subsequently transported to a tanker truck during the next filling of the underground storage reservoir (Phase I recovery). Thus, additional extensive piping would need to be located underground for vapor recovery from the dispensing units located at multiple service islands.
It is also desirable for automobile service stations to provide customers with at least some limited form of shelter from the weather, especially from precipitation. Service stations commonly provide one or more large canopies that extend over a substantial portion of the service station premises, covering the multiple service island locations as well as an extended amount of area surrounding the dispensing pumps. In this manner, service station customers are provided with the convenience of being able to stay dry while fueling, as well as while entering and exiting vehicles. Often, the canopy extends to provide a covered walkway to the service station attendant, who is commonly located within an adjacent service building, such as an automobile service garage or convenience store.
The canopies are typically suspended in place at some distance above the ground through the use of multiple support columns. These columns are often positioned adjacent the dispensing units upon one or more service islands upon the service station premises. Positioning the canopy support columns in this manner allows maximum maneuverability for automobiles upon the service station premises.
Further, the recent increased emphasis on environmental concerns has focused attention on the nature of, and environment surrounding, the underground storage reservoirs to minimize the leaking of fluids stored therein. A majority of conventional steel underground storage tanks are believed to leak due to electrolysis along the bottom of the tank. This is caused at least in part because the ground at the bottom of the tank is often wet and the weight of the tank and its contents cause solid contact with the soil, resulting in a condition that is favorable to the flow of electric current. Also, during such environmental events such as earthquakes and hurricanes, shifting of the underground storage reservoir, the pea gravel, sand or other fill material surrounding the tank, or introduction of excessive amounts of water to the area surrounding the tank, can each have negative effects on the tank, including leakage of the tank itself and leakage from the fluid delivery system due to disruption of the alignment of the delivery system relative to the reservoir.
A need therefore exists for an improved system whereby the need for extensive underground piping connecting underground fluid storage tanks and dispensing units can be eliminated. A need also exists for a simpler vapor recovery system for use in automobile service stations. A need also exists for an improved, simpler, less expensive system for constructing service station premises. A need further exists for an improved underground storage reservoir system having increased leak resistance, as well as increased resistance to the effects of earthquakes and hurricanes.